The present invention relates to a control apparatus for a drive system composed of an engine and a transmission, and in particular to a control apparatus for a drive system composed of an engine such as a gasoline engine or a Diesel-engine and a transmission such as an automatic transmission in combination of a torque converter and a gear train, or a belt-and-pulley type continuous variable transmission.
For example, Japanese Patent Publication No. 63-45977 and Japanese Patent Publication No. 63-45976 disclose therein a control apparatus which sets a desired wheel torque (which corresponds to a torque that can obtained at the final speed-change gear such as differential gear or a speed ratio between the engine speed and the wheel speed since the engine torque is substantially constant, irrespective of an engine speed, over an operating speed range) in accordance with an opening degree of the throttle valve of an engine which is manipulated by a driver. Further, it has been well-known that a control apparatus which sets the speed ratio in accordance with a torque of an engine.
In a conventional control apparatus for a drive system composed of an engine and a transmission, a desired wheel torque has been set in accordance with only an engine torque, irrespective of an air-fuel ratio (a fuel quantity in an engine cylinder), an intake valve closing angle, a supercharging pressure and a ratio between working and compression strokes, which are parameters for the engine torque. That is, since the desired torque has been directly set in relation to an engine torque and a vehicle speed, the consistence between the fuel economy and the acceleration performance has been difficult. Accordingly, in the case of the speed-up of a vehicle by changing the torque of an engine or that of a transmission, depending upon a taste of a driver (that is, whether he is fond of high acceleration or not) or a recognition of environment around the vehicle, the following problems have been raised, that is, should the acceleration performance be heighten while the torque of the transmission is maintained to be low with respect to an engine torque, the fuel economy would deteriorate. On the contrary, should the fuel economy be enhanced by increasing the torque of the transmission with respect to an engine torque, the acceleration performance would deteriorate.
Further, an in-cylinder fuel injection engine has been preferably used as an engine constituting the drive system in order to preform precise and complicated control. However, a conventional control apparatus has been adapted to control the timing of fuel injection and the timing of ignition under such a condition that the air volume is set to be constant. Accordingly, should an in-cylinder fuel injection engine having a ratio between working and compression strokes of less than 1 be controlled, the mixture would be locally overrich, causing generation of soot in the case of a large fuel injection volume, or the mixture would be excessively lean around a spark plug so as to cause the combustion unstable in the case of a small fuel volume. Further, if the fuel volume increases under such a condition that the air volume is constant, the air-fuel ratio decreases, causing increasing of nitrogen oxide (NOx) emission.
For example, an in-cylinder fuel injection engine disclosed in Japanese Laid-Open Patent No. 60-30420, incorporates a fuel injection valve directed to a spark plug, and an air injection value adapted to inject air which interferes with fuel injected from the injection valve, and accordingly, in the case of a less fuel induction volume during low load operation, air is injected into fuel jetted from the fuel injection valve to the spark plug so as to concentrate the fuel around the spark plug. In this arrangement, lean-burn operation and reduction of pumping loss can be carried out. However, since such an in-cylinder injection engine additionally requires the above-mentioned air-injection valve, not only the manufacturing cost of the engine is increased, but also unburnt hydrocarbon emission cannot be sufficiently reduced even with the provision of the above-mentioned arrangement.
The present invention is devised in view of the above-mentioned problems inherent to a conventional control apparatus for a drive system composed of an engine and a transmission, and accordingly, a first object of the present invention is to provide a control apparatus for a drive system composed of an engine and a transmission, which can perform flexible control so as to enhance both fuel economy and acceleration performance.
To the end, according to a first aspect of the present invention, a control apparatus for a drive system composed of an engine and a transmission is provided with a computing means for controlling the torque of the transmission and the air-fuel ratio of the engine in accordance with a desired wheel torque and a vehicle speed.
According to a specific form of the present invention, a control apparatus for a drive system is provided with a computing means for controlling the torque of a transmission and the closing angle of an intake valve in relation to each other in accordance with a desired torque and a vehicle speed. According to another specific form of the present invention, a control apparatus for a drive system is provided with a computing means for controlling the torque of a transmission and a supercharging pressure in relation to each other in accordance with a desired wheel torque and a vehicle speed, or a computing means for controlling the torque of a transmission and a ratio between working and compression strokes in relation to each other in accordance with a desired wheel torque and a vehicle speed.
The above-mentioned computing means carries out control operation in such a way that the fuel consumption and the acceleration performance are optimized with the use of a performance chart in accordance with a driver""s taste or an operating environment of a vehicle.
Further, a second object of the present invention is to provide a control apparatus for controlling an engine used in a drive system of a vehicle, preferably for controlling an in-cylinder fuel injection engine whose ratio between working and compression strokes can be set to be less than 1, which can prevent generation of soot, unstable combustion, and increasing of NOx emission.
To the end, according to the present invention, the control apparatus for an internal combustion engine comprises a fuel injection timing control means for controlling the volume of fuel injected from a jet port of a fuel injection device which is located in a combustion chamber of the engine, and the fuel injection timing, and an intake valve opening and closing control means for controlling the opening and closing timing of an intake valve of the engine, the fuel injection timing control means controlling the volume of the fuel and the fuel injection timing in accordance with a variation in air volume to be burnt in the combustion chamber.
Further, a third object of the present invention is to provide a preferable fuel injection valve for the above-mentioned engine, which can reduce the manufacturing cost of the engine, which can reduce the emission of unburnt hydrocarbon as far as possible, and which can exhibit stable combustion over a wide operating range of the engine.
To the end, according to the present invention, the fuel injection valve comprises a means for injecting fuel in a decreased injection splay angle, and a means for injecting fuel in an increased injection splay angle.
Specific explanation will be hereinbelow made of specific embodiment forms of the present invention with reference to the accompanying drawings in which: